Chess in a Few Bytes
Linux has a good range of extremely strong chess engines such as Stockfish, Critter, Togo II, Crafty, GNU Chess, and Komodo. The chess engines featured in this article offer no match to a good chess engine, but they show how much can be achieved with a minuscule codebase.

by Craig Hunt: Linux Sendmail Administration is the most complete, most advanced guide to Sendmail you'll find anywhere. Written by one of today's most renowned Linux experts, this book teaches you, step-by-step, all the standard and advanced techniques you need to know to install, configure, and maintain Sendmail. UK, Germany

by Bryan Costales, Claus Assmann, George Jansen, Gregory Neil Shapiro: A classic O'Reilly title since 1993, sendmail now covers Versions 8.10 through 8.14 of this email routing program, including dozens of new features, options, and macros. UK, Germany